I would leave from Biscayne Bay. There is a little harbor on South Biscayne everybody uses for their last anchorage in FL before jumping off. It's been a while, can't
recall the name offhand, but it's well known. It's part of a state or national park. From there,
Bimini is easy. Just factor in the northward drift, so your course should not be directly to
Bimini, but "crabbing" a bit for the offset.
As far as the dingy, I would NOT tow across the Gulfstream. Too iffy. I'd deflate the
rib and put it on
deck where ever I could. Once in Bimini, go ahead and tow it around the
Bahamas, but leave it's self-bailing drain hole open to clear out spray, otherwise it can fill up with
water and get very, very heavy, putting too much stress on your towline, and especially on the bow ring which is essentially just glued to the bow of the
RIB. If you have a ring bolted through the
fiberglass, that is stronger. If not, attach your tow line not only to the bow ring, but to your side carry handles, and then to your transom. Let the bow ring just be the "guide" for the
bridle which will will absorb the forces through the side carry handles, and back to the transom.
With the drain hole open and a good towing
bridle, you will have no trouble in the
Bahamas. But for the Gulfstream, I'd put the RIB on
deck for sure.